/Engine/Source/Editor/BlueprintGraph/Classes/EdGraphSchema_K2.h
Do validation, that doesn't require a knowledge about actual pin
virtual bool DefaultValueSimpleValidation ( const [FEdGraphPinType](API\Runtime\Engine\EdGraph\FEdGraphPinType) & PinType, const [FName](API\Runtime\Core\UObject\FName) PinName, const [FString](API\Runtime\Core\Containers\FString) & NewDefaultValue, [TObjectPtr](API\Runtime\Core\Delegates\TObjectPtr)< [UObject](API\Runtime\CoreUObject\UObject\UObject) > NewDefaultObject, const [FText](API\Runtime\Core\Internationalization\FText) & InText, [FString](API\Runtime\Core\Containers\FString) * OutMsg ) const